I'm not familiar with baseball (Belgian here) and was wondering how these things are regulated? Does each player have its own bat? So one team can already be at a technological disadvantage when the game starts?
Regarding the bat itself, the regulations say it must be "round" (1.10), which probably rules out this particular handle. Other than round, the maximum weight, length, and diameter are specified. While bats close to these maximums were once widely used, almost all modern bats are well shy of those figures. Presumably the lighter, smaller bats of today more than make up in control and speed what they lack in mass.
[0] http://mlb.mlb.com/mlb/downloads/y2010/official_rules/2010_O...
I saw them for the first time this summer. We were in the US for a bit and I had the chance to get my son some batting instruction. (We live in Hungary and he plays little league here but it's harder to find coaches and such.) We did it with a friend and his son uses these bats. They are expensive. The wooden Axe bat he was using is around $100. And those only last so long. But anyway - when you have people dropping $300 - $500 on softball bats it's not hard to see how a company can do well selling to recreational players.
If the power and accuracy claims hold up then it could also help level out the current status of the game being tilted in favor of pitching since the end of the steroid era. There had been talk of lowering the mound in the MLB to help level the playing field, mind the pun :)
It is definitely an interesting concept. I'm not sure how well the bat will hold up over time vs a traditional bat since you are hitting the ball the on the same side every time. This is going to slightly flatten the face of the bat over time and it will be interesting to see how that plays out.